Externally controlled sawtooth generator with variable pulse duration and constant amplitude

ABSTRACT

A circuit arrangement for producing a sawtooth voltage, of constant amplitude and a variable slope of the front flank by charging and discharging a condenser. To maintain the amplitude of the sawtooth voltage constant with a varying periodic time of a cycle determined by a synchronizing signal having a certain periodic time, first circuit means produce a voltage corresponding to the respective periodic time of the synchronizing signal, second circuit means store this voltage during a cycle, and additional circuit means control the charging current of the condenser as a function of this voltage. The charging current of each sawtooth voltage cycle or pulse is always controlled by the voltage derived from a preceding cycle or pulse of the synchronizing voltage. In order to keep the error, appearing with relatively rapid frequency variations with corresponding rapid variations of the periodic time of the synchronizing voltage, in the instantaneous voltage course of the sawtooth signal, negligibly small, additional circuit means add, to a cycle of the synchronizing signal, a differential voltage derived from the aforementioned voltage and the voltage corresponding to a respective preceding cycle. This additional circuit means adds a certain &#39;&#39;&#39;&#39;lead&#39;&#39;&#39;&#39; to the variation of the slope of the sawtooth signal.

United States Patent 2,854,575 9/1958 Richardson 328/181 3,217,27111/1965 Autorino eta1.... 328/185X 3,373,377 3/1968 Townsend 328/185XPrimary Examiner-Stanley D. Miller, Jr. Attrney-McGlew and TorenABSTRACT: A circuit arrangement for producing a sawtooth voltage, ofconstant amplitude and a variable slope of the front flank by chargingand discharging a condenser. To maintain the amplitude of the sawtoothvoltage constant with a varying periodic time of a cycle determined by asynchronizing signal having a certain periodic time, first circuit meansproduce a voltage corresponding to the respective periodic time of thesynchronizing signal, second circuit means store this voltage during acycle, and additional circuit means control the charging current of thecondenser as a function of this voltage. The charging current of eachsawtooth voltage cycle or pulse is always controlled by the voltagederived from a preceding cycle or pulse of the synchronizing voltage.

In order to keep the error, appearing with relatively rapid frequencyvariations with corresponding rapid variations of the periodic time ofthe synchronizing voltage, in the instantaneous voltage course of thesawtooth signal, negligibly small, additional circuit means add, to acycle of the synchronizing signal, a differential voltage derived fromthe aforementioned voltage and the voltage corresponding to a respectivepreceding cycle. This additional circuit means adds a certain lead tothe variation of the slope of the sawtooth signal.

SAWTOOTH ARRANGEMEN/ [72] inventor Josef Hainz Ottobrunn, Germany [21]Appl. No. 682,815 [22] Filed Nov. 14, 1967 Patented Mar. 23, 1971 [73]Assignee Bolkow Gesellschaft mit beschrankter Raining, Ottobrunn, nearMunich, Germany [32] Priority Nov. 19, 1966 [33] Germany [31] B89909[54] EXTERNALLY CONTROLLED SAWTOOTH GENERATOR WITH VARIABLE PULSEDURATION AND CONSTANT AMPLITUDE 9 Claims, 11 Drawing Figs. [52] US. Cl307/228, 307/229, 328/181, 328/185 [51] Int. Cl 111031: 4/50 Field ofSearch 328/181- [56] References Cited UNITED STATES PATENTS 2,492,01812/1949 Sunstein 328/183X 2,562,188 7/1951 328/185 2,581,199 l/l952328/185X 2,596,167 5/1952 328/185 2,645,715 7/1953 328/183X H SYNC. 0-.U SIGNAL PULSE FORMING STAGE FUNCTION GENERATOR DIFFERENCE CIRCUIT ae LTr T l 1 GATE CIRCUIT PATENIEI] IIIII2 3 IIIII 3,571.61?

SHEET 1 U? 4 Fig.1

1 SAWTOOTH 5 ARRANGEMEV H c SYNC. SIGNAL H U i M 5%}; FORM'NG DIFFERENCE2 CIRCUIT .s FUNCTION GENERATOR r" I L I' I E J E GATE CIRCUIT STORAGEINVENTOR Josef HcIInz WZWMIM ATTORNEYS ATENIEU M23 1971 SHEET 2 BF 4Fig.2 6 +U I O INVENIOR Josef Hcunz WWW M ATTORNEYS ATENTEDmzam:3.571.617

sum 3 or 4 Fig.3

JWAV a A 31 12 3 VEN TOR Jos Hcunz ATTORNEYS PATENTED m2: m

SHEET 8 OF 4 Input H INVENTOR Josef Huinz ATTORNEYS EXTERNALLYCGNTROLLED SAWTGOTH GENERATOR WlTi-i VARIABLE EULSE DURATIGN ANDQONSTANT AMPMTUDE BACKGROUND OF THE INVENTION Clrcuit arrangements forproducing sawtooth voltages operate on the principle of charging acondenser from a current source and discharging the condenser through adischarge circuit utilizing the effect that a condenser charged withconstant current varies its voltage linearly. The voltage across thecondenser is tapped to provide the sawtooth voltage. For varying thesawtooth voltage, it is known to vary the capacity of the condenser, theresistance in the charging circuit, or both, so that the time constantcontrolling the charging of the condenser is variable. For example, seeGerman Pat. No. 1,138,095

The periodic time of the cycle, which is the frequency of the sawtoothvoltage, also varies, because the peak value of the sawtooth voltage isattained either earlier or later. When the peak value of the sawtoothvoltage is attained, the condenser is discharged to produce the rear ortrailing flank of the sawtooth signal or pulse.

In guiding missiles, each rotating about its own axis with a certainrolling frequency, it has been proposed to use a linear sawtooth signalof constant amplitude to determine the instantaneous angular position ofthe missile about its axis. The rotating missile produces, at the end ofa full revolution, a reference pulse, so that the cycle of the referencepulse corresponds to a rotation of the missile through 360.

in order to determine the rotary positions of the missile between theand 360 positions, a linear sawtooth voltage of constant amplitude isderived from the reference pulse, which has the same phase and frequencyas the reference signal. A definite angular position of the missile,corresponding to a definite angle of rotation of the missile, isassociated with each respective instantaneous value of the linearsawtooth voltage. However, since the rolling frequency of the missile isnot constant in each flying phase, both the frequency and the cycle ofthe reference signal vary, resulting in variation of the sawtoothvoltage. Nevertheless, since the slope of the sawtooth voltagedetermined by the charging time constant is constant, the amplitude ofthe sawtooth voltage likewise varies with variation of the frequency, sothat the respective angular position of the missile can no longer bedetermined with sufficient accuracy.

In guiding missiles, and in other applications of control and regulatingtechnique, extremely linear sawtooth voltages are consequently required,and these must have respective instantaneous voltages which are the samefor any value of a cycle, and thus independent of the frequency of eachcycle. In an arbitrary variation of the sawtooth voltage caused, forexample, by a synchronizing signal, that is, with a different cycle, theslope of the sawtooth voltage must also be varied correspondingly sothat the peak value of the sawtooth voltage, attained at the end of eachcycle, is constant.

SUMMARY OF THE INVENTION This invention relates to the generation ofsawtooth voltages and, more particularly, to an improved and simplifiedcircuit arrangement for producing a sawtooth voltage of constantamplitude and variable slope of the front flanks of sawtooth pulses, bycharging and discharging a condenser.

In accordance with the invention, such a circuit arrangement is providedand works with a very short delay time to so vary the respective slopesof sawtooth voltages or pulses, to the extent of available duration of acycle as determined, for example, by a synchronizing signal, and hencethe frequency of the sawtooth voltage, that the values of the respectiveinstantaneous voltages of the sawtooth pulses are the same for allcycles for any value between 0 and 211- of a cycle and independent ofthe duration of the cycle.

The basis of the invention improvement is a circuit arrangement forproducing sawtooth voltages of constant amplitude and variable slope ofthe front flanks of pulses by charging and discharging a condenser. Inaccordance with the invention, in order to keep the amplitude of thesawtooth voltage constant with varying duration or periodic time of acycle determined by a synchronizing signal with a predetermined periodictime, first circuit means are provided for producing a voltagecorresponding to the respective periodic time of the synchronizingsignal, second circuit means are provided for storing this voltageduring a cycle, and additional circuit means are provided forcontrolling the charging current of the condenser as a function of thisvoltage. The charging current of a sawtooth voltage cycle or pulse isalways controlled by the voltage derived from a preceding cycle or pulseof the synchronizing voltage.

Using the circuit arrangement of the invention, it is possible to setthe slope of the sawtooth voltage pulses exactly according to theamplitude of the respective preceding pulse, in order to maintain theamplitude of the sawtooth voltage pulses automatically constant withvarying periodic times as determined by a synchronizing signal. Thus, inthe case of a frequency variation of the synchronizing signal, and thusof a frequency variation of the sawtooth voltage or signal, therespective instantaneous voltages of the sawtooth signal pulses asdetermined by the slope of the front flank thereof differ only by thevariation of the periodic time in two successive cycles.

In the invention circuit arrangement, an analogous value correspondingto the cycle of the synchronizing cycle is formed by a simple andreliable circuit means, and appears in the form of a voltage. Thisvoltage is stored and is available in the next cycle of thesynchronizing signal, and thus for the next or succeeding sawtoothsignal pulse, for controlling the charging current of the condenser usedfor producing the sawtooth voltage. During each cycle, the condenser isfed or supplied with a constant charging current whose amplitude, for arespective pulse, is determined, however, by the duration of arespective preceding pulse.

ln order to keep the error, appearing with relatively rapid frequencyvariations and thus rapid variations in the oscillation time of thesynchronizing signal, in the instantaneous voltage value of a sawtoothsignal negligibly small, additional circuit means are provided, inaccordance with a feature of the invention, to add, to a cycle of thesynchronizing signal, a differential voltage derived from the initialvoltage and the voltage corresponding to the respective preceding cycleof the synchronizing voltage. By virtue of such additional circuitmeans, a certain lead" is added to the variation of the slope of thesawtooth signal pulse, and resulting from a current variation of theduration of the cycle. The amplitude of this lead depends on therelative variation of the duration from cycle-to-cycle of thesynchronizing signal.

An object of the present invention is to provide an improved circuitarrangement for generating sawtooth voltages and working with a veryshort delay time as well as being operable to vary the respective slopesof sawtooth voltage pulses to the extent of the available duration of acycle as determined, for example, by a synchronizing signal.

A further object of the invention is to provide a circuit atrangementfor producing sawtooth voltages in which the amplitude of the respectiveinstantaneous voltages of the sawtooth signals or pulses is the same forall cycles for any value between 0 and 21:- of a cycle and independentof the duration of a cycle.

Another object of the invention is to provide such a circuit arrangementincluding first circuit means for producing a voltage corresponding tothe respective periodic tim of oscillation of a synchronizing signal,second circuit means for storing this voltage during a cycle, andadditional circuit means for controlling the charging current of thecondenser as a function of this voltage.

Still another object of the invention is to provide such a circuitarrangement in which the charging current of a sawtooth voltage cycle orpulse is always controlled by the voltage derived from a preceding cycleof the synchronizing voltage.

A further object of the invention is to provide such a circuitarrangement with which it is possible to adjust the slope of thesawtooth voltage pulses exactly according to the amplitude of therespective preceding cycle in order to maintain the amplitude of thesawtooth voltage pulses automatically constant with varying duration ortime periods as determined by synchronizing signals.

Yet, another object of the invention is to provide such a circuitarrangement in which, in case of a frequency variation of thesynchronizing signal and thus of the sawtooth signal, the respectiveinstantaneous voltage of the sawtooth signal, as determined by the slopof its leading flank, differs only by the variation of the duration intwo successive cycles.

A further object of the invention is to provide such a circuitarrangement in which a value analogous and corresponding to the cycle ofthe synchronizing signal is formed by simple and reliable switchingmeans and in the form of a voltage.

Yet, another object of the invention is to provide such a circuitarrangement in which this voltage is stored and is available in the nextcycle of the synchronizing signal, and thus of the sawtooth signal, forcontrolling the charging current of the condenser used to produce thesawtooth voltage.

A further object of the invention is to provide such a circuitarrangement in which the condenser is fed during each cycle with aconstant charging current whose amplitude, for this respective cycle, isdetermined by the duration of the respective preceding cycle or pulse.

Another object of the invention is to provide such a circuit arrangementin which the errors, appearing with relatively rapid frequencyvariations and thus rapid variations of the periodic time of oscillationof the synchronizing signal, in the instantaneous voltages of thesawtooth signals are negligibly small, by utilizing additional circuitmeans which add, to a cycle of the synchronizing signal, a differentialvoltage derived from this voltage and the voltage corresponding to therespective preceding cycle or pulse.

A further object of the invention is to provide such a circuitarrangement in which a certain lead is added to the variation of theslope of a sawtooth signal pulse, resulting from a current variation ofthe duration of the cycle, and whose amplitude depends on the relativevariation of the duration from cycle-to-cycle of the synchronizingsignal BRIEF DESCRIPTION OF THE DRAWINGS For an understanding of theprinciples of the invention, reference is made to the followingdescription of a typical embodiment thereof as illustrated in theaccompanying drawings.

FIG. 1 is a block diagram of a circuit arrangement embodying theinvention;

FIGS. 2 and 3, when placed side-by-side, form a schematic circuitdiagram of an embodiment of the invention designed using semiconductortechnology; and

FIGS. 4a through 4h are waveform timing diagrams of the embodiment ofthe invention illustrated in FIGS. 1, 2 and 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a pulseforming stage 1 receives, at its input, the synchronizing signal H andprovides, at its output, pulses which are supplied to additional circuitmeans. The duration of the cycle determined by synchronizing signal H isdetermined by two successive pulses. Pulses from pulse forming stage 1are supplied to a function generator 2, a gate circuit 3 and a circuitarrangement 5 which forms the sawtooth signal proper. Function generator2 forms a voltage course which is initiated by a first pulse andterminated by a second pulse supplied from pulse former stage 1. Thevoltage course or characteristic formed in function generator 2 bysuitable circuit means has the form u =U,A/t, where U and A arecircuit-dependent constants, and a is the instantaneous voltageappearing at any time. At the end of a cycle, that is, at the time r=T,when the respective second pulse from the pulse former stage 1 reachesfunction generator 2, there is an output voltage U at the output offunction generator 2 and which corresponds to the cycle time T. Thisvoltage U is supplied, through gate circuit 3 which transmits onlyduring a pulse provided by pulse former stage 1, to storage 4 where thevoltage is available during the entire following cycle. This voltage,accumulated at storage 4, now determines the amplitude of the chargingcurrent for the circuit means 5 which produces the sawtooth signalproper.

A circuit arrangement 6 may be provided between function generator 2 andgate circuit 3, and adds a certain voltage to the voltage U at theoutput of function generator 2. This voltage, added by circuitarrangement or means 6, is determined by the difference of two voltagesU and U at the output of function generator 2, and which correspond tothe duration of two successive cycles of the synchronizing signal H.

In the schematic diagram shown in FIGS. 2 and 3, the pulse former stage1, illustrated in FIG. 2, includes a transistor T whose emitter iscontrolled by synchronizing signal H. A winding in of a transformer U isarranged in the collector circuit of transistor T this winding beingincluded in the block 2 as designated in FIG. 2. Transformer U has awinding n connected in the base circuit of transistor T and hasadditional windings n and n Gate circuit 3, which comprises diodes D D Dand D is controlled by winding u and winding n controls another gatecircuit, in block 6 of FIG. 2, comprising diodes D D D and D A negativepulse of synchronizing signal H appearing at the emitter of transistor Ttriggers this transistor conductive, and transistor T is kept conductivethrough windings n, and n of the transformer and which are connected,respectively, in the base circuit and in the collector circuit.Transistor T is maintained conductive until the magnetism of the core oftrans former U is reversed. As a result of this reversal, a pulseappears at winding n and, during the duration of this pulse, the chargeof condenser C (function generator 2) is reversed through diode D Thepulse at winding n reverses the magnetism of the core of transformer U.

Upon reversal of the magnetism of the transformer core, transistor T istriggered nonconductive or to a blocking state, and the thus rechargedcondenser C triggers conductive a transistor T whose base is connectedto condenser C Together with a transistor T transistor T forms amonostable multivibrator which, after a short time, returns to itsstable position in which transistor T conducts and transistor T blocks.During the short time in which transistor T is conductive, a condenser Cis discharged through diode D and the collector-emitter circuit oftransistor T During the longer blocking time of transistor T condenser Cis charged through a resistance combination consisting of resistors R RR and R and diodes D and D These resistors R6R9 are so dimensioned thatthe voltage formed during the charging of condenser C corresponds to thefunction u =U,A/t.

Momentarily neglecting the switching arrangement 6, and considering thepoints A and B of FIG. 2 as being directly connected, the voltagecharged on condenser C is applied, through an impedance transformerconsisting of transistors T T and T to the input of gate circuit 3. Thisgate circuit 3 is formed by diodes D D D and D During the succeedingconductive period of transistor T responsive to the succeeding negativesynchronizing pulse, gate circuit 3 is opened by a pulse appearingacross winding n Thereby the voltage charged on condenser C is appliedto condenser C shown in FIG. 3, which performs the function of storage4.

The voltage charged on condenser C is applied to condenser C through acircuit including the impedance transformer composed of transistors T Tand T to the point A and thence, if points A and B are interconnected,as shown in FIG. 1, to point B and subsequently through gate circuit 3and point E to condenser C as shown in FIG. 3. On the other hand, ifpoints A and B are not directly interconnected, the voltage charged oncondenser C as applied to point A, is applied through the gate circuitof component 6, composed of diodes D D D and D, to condensers C and Cand, from these condensers, through another impedance transformercomposed of transistors T T and T to point B and thence, as describedabove, to condenser C During the cycle initiated by the opening effectedby this last pulse, the voltage stored on condenser C is applied,through an impedance transformer consisting of transistors T,,,, T,,, Tand T,;,, to the base of a transistor T A condenser C is connected inthe collector circuit of transistor T and serves to produce the sawtoothvoltage. Condenser C is charged through transistor T H with a currentwhich is constant during each cycle, and the value of this current isdetermined by the amplitude of the respective voltage applied to thebase of transistor T The voltage characteristic across condenser C ismade available, through an additional impedance transformer consistingof transistors T,,,, T and T,,,, at the outputs C, as the sawtoothsignal proper.

Condenser C, is bridged by the collector-emitter circuit of a transistorT whose base is connected through a condenser C and a resistor R withwinding n, of transformer U. Through resistor R and a diode D and thebase-emitter circuit of transistor T respectively, condenser C is sorecharged periodically that it triggers transistor T conductive, throughthe base of the latter, during the conductive period of transistor T andthus with the appearance of a pulse at winding n Condenser C is abruptlydischarged through the collector-emitter circuit of the openedtransistor T that is, during the appearance of a pulse. This dischargecorresponds, in each case, to the rear flank of a sawtooth voltage 30pulse whose front flank is determined by charging of condenser Ceffected through resistor R and transistor T,,,.

The switching circuit 6, shown in FIG. 2 as connected between the pointsA and B, operates in the following manner. At the end of each cycle,that is, during the opening or triggering conduc ive of transistor T agate circuit, consisting of diodes D D D and D is opened throughwindings n Thereby, a condenser C is charged to the voltage at point A,which corresponds to the duration of the respective immediatelypreceding cycle. If the duration of the immediately preceding cycle isdesignated T,,, condenser C is charged to a voltage U corresponding tothis duration. During the next cycle, having the duration T,, the gatecircuit remains blocked so that voltage U is stored unchanged incondenser C At the base of transistor Tl which base is also connectedwith point A, there appears the voltage U of functional generator 2whose output voltage, at the end of this cycle, has the value U Beforethe gate circuit consisting of diodes D D [is again opened at the end ofthe cycle having the duration TM, by brief opening or conductivity oftransistor T9, a voltage AU ,,,,=U ,U appears on condenser C3. When thegate circuit is opened, condenser C2 is charged very rapidly to thevoltage U which corresponds to the duration T,,, Thus the voltage AUstored additionally in condenser C3 is applied to the base of transistorT1 in addition to the voltage U Transistor Tl comprises part of animpedance transformer including transistors T2 and T3. Thus, a voltage UU fi appears at gate circuit 3 through point B. In the immediatelypreceding equation, k is a circuit-dependent constant.

Due to the provision of switching circuit 6 connected between points Aand B, a voltage AU is added to the voltage U corresponding to therespective duration of the cycle, with voltage AU corresponding to therespective variation of the durations of two successive cycles. Thisassures that, in case of a frequency variation, that is, a variation ofthe duration of several successive cycles, the control of the leading orrising flank of a sawtooth signal pulse receives a certain lead. Anyerror resulting in the determination of the size of the slope of thesawtooth signal pulse in accordance with the duration of the respectivepreceding cycle is thus reduced in the sense of the anticipatedvariation of the duration between two successive cycles.

through transistor R M This has the result that the indication of theangular position of a missile rotating about its own axis, and which isnecessary for certain missile guiding procedures is given withsufficient accuracy by the respective instantaneous values of a linearsawtooth voltage, even in the case of a variation of the rotationalfrequency. Any variation of the duration of the sawtooth voltage, causedby variation of the rotation of frequency of the missile, effects avariation of the slope of the sawtooth voltage so that its instantaneousvalue is equal for all cycles for any value between 0 and 211' of acycle, independent of the duration.

Referring to the pulse or waveform diagrams shown in FIG. 4a 4h, FIG. 4athe first line illustrates the pulses transmitted to the input H of thepulse forming stage 1, and which are emitted, for example, with everyfull revolution of a missile rotating about its longitudinal axis, andthrough the medium of a corresponding gyroscope. Pulse forming stage 1transforms these input pulses into narrow rectangular pulses asillustrated in FIG. 4b, and these narrow rectangular pulses serve tocontrol various components of the circuit arrangement and which arecoupled through windings n n and n, of transformer U which includes thewinding n of pulse former stage 1.

FIG. 40 illustrates the rectangular signal appearing at the output ofthe multivibrator comprising transistors T and T As can be seen,transistor T conducts during a relatively short time, while themultivibrator is in its unstable state, so that condenser C,- isdischarged through the then conducting transister T and the diode D If,after expiration of this relatively short time, the multivibratorswitches back to its stable state, in which transistor T is conductingand transistor T is blocked, then condenser C is no longer shortcircuited The voltage u appearing across condenser C is illustrated inFIG. 4d. As can be seen from the time correlation with the signal shownin FIG. 40, condenser C is discharged during the unstable state of themultivibrator, and it is charged after the stable state of themultivibrator is reached, according to a certain function which isdetermined by function generator 2 comprising diodes D D and resistors RR R and R As will be noted the multivibrator comprising transistors Tand T is switched to an unstable state again upon appearance of the rearflank of a new rectangular pulse at winding n whereby condenser C isagain discharged. Upon appearance of the front flank of each rectangularpulse, as shown in FIG. 4b, there are opened, simultaneously, gatecircuit 3 comprising diodes and the gate circuit in component 6, owingto which the peak voltage U attained at condenser C is applied tocondenser Cg. The voltage available at condenser C is shown in FIG. 4e.W

Independently of the opening of the gate circuit contained in component6, the voltage available at all times at condenser C is applied, throughthe impedance transformer comprising transistors T T and T through thepoint A and through resistor R to condenser C at which the voltage shownin FIG. 4f appears. When condenser C is discharged, there is formed atcondenser C as viewed from point A, the same voltage as at condenser Cbut with an opposite sign, so that the voltage rising at condenser C isthen drawn continuously. Upon occurrence of each rectangular pulse,therefore, there is available, at condenser C precisely a voltage whichcorresponds to the difference of the voltages produced, during twosuccessive period durations, at condenser C The period durations ofperiod n and of the following period n+1 are exactly equal so that, aswill be noted from FIG. 4f, the voltage appearing at condenser C when arectangular pulse occurs at the end of the periods is exactly equal tozero.

With the occurrence of each rectangular pulse, the voltage available atcondenser C plus the voltage just then available at condenser C isapplied, through the impedance transformer comprising transistors T Tand T through point B, and through gate circuit 3 to condenser C shownin FIG. 3. This voltage, occurring at condenser C is shown in FIG. 4g.

With further reference to FIGS. 4a4h the period durations of the thirdperiod n+2 therein illustrated and of the fourth period n+3 are longerthan the first two period durations. For this reason, also the voltagesU and U produced through the function generator at condenser C duringthese period durations, are greater than the voltages U and U producedin the preceding period durations. Therefore, these larger voltages arepresent at condenser C as can be seen from FIG. 4e. Since the thirdperiod n+2 is thus longer than the second period n+1, and the fourthperiod n+3 longer than the third period n+2, there appears, uponoccurence of a rectangular pulse at the end of the third period, atcondenser C the voltage attained at the end of the second period or,respectively, the difference of the voltage attained at the end of thefourth period and the voltage attained at the end of the third period.These difference voltages A U are illustrated in FIG. 4f.

The voltage applied to condenser C upon occurrence of a rectangularpulse at the end of the third period and at the end of the fourthperiod, consequently is greater not only by the amount by which thevoltage at condenser C at the end of the third or fourth period hasincreased as compared with preceding periods, but also by the additionalvoltage amount available at condenser C upon occurrence of a rectangularpulse. By this added additional voltage quantity, there is attainedthat, at a continuous variation of successive periods, a certain reserveis produced. This takes into consideration that the sawtooth voltagepulse just emitted normally shows a slope which is determined accordingto the duration of the preceding periods. This behavior of the circuitarrangement is illustrated in FIG. 4h which shows the sawtooth voltageemitted at the output C of the circuit arrangement.

As can be seen from FIG. 4h, the voltage configuration emitted duringthe first period n and the second period n+1 are identical and the endvalues have exactly the specified amplitude. On the other hand, thevoltage configuration emitted during the third period n+2 attains asomewhat higher amplitude, as the rise time of this signal still dependson the duration of the immediately preceding period n+1, and thereforecoincides therewith, although the length of period n+2 is alreadygreater than that of the preceding period. Due to the reserve becomingoperative at the end of the third period n+2, as shown in FIG. 4h, theemitted sawtooth voltage again attains exactly its specifiedconfiguration during the fourth period n+3.

If component or circuit arrangement 6 were not present, as if terminalsA and B were directly interconnected, then, although the slope of thesawtooth signal emitted during the fourth period n+3 would be smallerthan that of the sawtooth signal emitted during the third period n+2,the amplitude of the sawtooth signal occurring during the fourth periodn+3, would still be greater than the desired amplitude, since also thelength of the fourth period is greater than that of the third period.

While a specific embodiment of the invention has been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

Iclaim:

1. In circuitry for producing a sawtooth voltage, of constant amplitudeand variable slope of the leading flanks of the sawtooth pulses, bycharging and discharging a condenser:

a circuit arrangement automatically maintaining constant the amplitudeof the sawtooth voltage pulses despite varying variation of cyclesdetermined by successive synchronizing signals applied to the input ofsaid circuitry, said circuit arrangement comprising in combination,first circuit means having said synchronizing signals applied to itsinput and producing output voltages U corresponding to the respectivedurations T of cycles between successive synchronizing signals;

second circuit means, including a gate circuit having its inputconnected to said first circuit means, and storage means connected tothe outputof said gate circuit and operable to store the output voltageU,, produced during a respective cycle; and

third circuit means connected to said first and second circuit means andcontrolling the charging current of said condenser, during each cycle T,as a function of the amplitude of the stored output voltage U producedduring the immediately preceding cycle T of said synchronizing signals,n being a whole number designating a base cycle; whereby the sawtoothsignal pulse emitted during each cycle is controlled in proportion tothe length of the immediately preceding cycle T,, between successivesynchronizing signals.

2. A circuit arrangement, as claimed in claim 1, including fourthcircuit means connected to said first and second circuit means andderiving, from the output voltage U corresponding to a cycle T betweenthe synchronizing signals, and the output voltage U corresponding to theimmediately preceding cycle T between the synchronizing signals, adifferential voltage AU and adding said differential voltage AU to saidoutput voltage UR.

3. A circuit arrangement, as claimed in claim 1 in which said firstcircuit means, providing an output voltage U corresponding to the cycleT between said synchronizing signals, includes a monostablemultivibrator; and a second condenser connected to said multivibratorand having its charging controlled by said multivibrator to produce acharge voltage u U A/t, in which U and A are circuit constants and t isthe instantaneous value of the charging time of said second condenser.

4. A circuit arrangement, as claimed in claim 3, including fourthcircuit means connected to said first and second circuit means meansconnected to said first and second circuit means and deriving, from theoutput voltage U corresponding to a cycle T between the synchronizingsignals, and the output voltage U corresponding to the immediatelypreceding cycle T between the synchronizing signals, a differentialvoltage AU and adding said differential voltage AU R" to said outputvoltage U 5. A circuit arrangement, as claimed in claim 1, in which saidthird circuit means comprises as olid state current device controllingthe charging current of said first-mentioned condenser, and a transistorconducting the discharge current of said first-mentioned condenser andconnected in parallel with said first-mentioned condenser.

6. A circuit arrangement, as claimed in claim 5, in which said firstcircuit means, providing an output voltage U corresponding to the cycleT between said synchronizing signals, includes a monostablemultivibrator; and a second condenser connected to said multivibratorand having its charging controlled by said multivibrator to produce acharge voltage u U A/t, in which U and A are circuit constants and t isthe instantaneous value of the charging time of said second con denser.

7. A circuit arrangement, as claimed in claim 6, including a transformerhaving a magnetizable core and a plurality of windings on said core;said first circuit means including a pulse forming stage having saidsynchronizing signals applied to its input and including a secondtransistor having an electrode connected to the input of said pulseforming stage and connected by a feedback circuit to first and secondwindings of said transformer; said monostable multivibrator comprising apair of third transistors and being connected to said first transformerwinding for control by the latter; a third condenser connected to saidmultivibrator and periodically charged and discharged by saidmultivibrator, a fourth condenser; a first impedance transforming means,consisting of a plurality of transistors, and a first gate circuit,consisting of a plurality of diodes and connected to a third winding ofsaid transformer for control by said third winding, connecting saidfourth condenser to said multivibrator; said multivibrator, responsiveto a pulse corresponding to a synchronizing signal, transferring thecharge of said third condenser to said fourth condenser for storage insaid fourth condenser; a second impedance transforming means consistingof a plurality of transistors connecting said fourth condenser with thebase of a fourth transistor controlling the charging current of saidfirst-mentioned condenser producing the sawtooth voltage; thecollector-emitter circuit of said first transistor being connected inparallel with said first-mentioned condenser, and the base of saidtransistor being connected to said first winding of said transformer;said first transistor being triggered conductive briefly responsive to apulse of said synchronizing signals being applied to its base by saidfirst winding; a sawtooth voltage output terminal included in said thirdcircuit means; and a third impedance transforming means, consisting of aplurality of transistors, connecting said first-mentioned condenser tosaid sawtooth voltage output terminal to provide sawtooth voltage pulsesat said sawtooth voltage output terminal.

8. A circuit arrangement, as claimed in claim 7, including fourthcircuit means connected to said first and second circuit means andderiving, from the output voltage U corresponding to a cycle T betweenthe synchronizing signals, and the output voltage U corresponding to theimmediately preceeding cycle T between the synchronizing signals, adifferential voltage AU and adding said differential voltage AU to saidoutput voltage U 9. A circuit arrangement, as claimed in claim 8, inwhich said fourth circuit means includes an input terminal, a secondgate circuit, consisting of a plurality of diodes, connected to saidlast-named input terminal, a fourth winding of said transformerconnected to and controlling said second gate circuit and a fifthcondenser connected to the output of said second gate circuit; saidfifth condenser storing the voltage applied to said last-named inputwhen said second gate circuit is opened; a fourth impedance transformingmeans, consisting of a plurality of transistors including a fifthtransistor as its input; a sixth condenser connecting the base of saidfifth transistor to said fifth condenser; means connecting the base ofsaid fifth transistor to said last-named input terminal; said sixthcondenser being charged with the voltage difference between the voltagestored in said fifth condenser and the instantaneous voltage at saidlast-name input terminal; an output terminal connected to the lasttransistor of said fourth impedance transforming means, whereby avoltage which is the sum of the voltage difference charged on said sixthcondenser and the voltage stored in said fifth condenser is applied tosaid last named output terminal during opening of said second gatecircuit and through said fourth impedance transforming means; saidlast-named input tenninal being connected with the output of said firstimpedance transforming means and said lastnamed output terminal beingconnected with the input of said first gate circuit; whereby said fourthcircuit means is interposed between the output of said first impedancetransfonning means and the input of said first gate circuit.

1. In circuitry for producing a sawtooth voltage, of constant amplitudeand variable slope of the leading flanks of the sawtooth pulses, bycharging and discharging a condenser: a circuit arrangementautomatically maintaining constant the amplitude of the sawtooth voltagepulses despite varying variation of cycles determined by successivesynchronizing signals applied to the input of said circuitry, saidcircuit arrangement comprising in combination, first circuit meanshaving said synchronizing signals applied to its input and producingoutput voltages UR corresponding to the respective durations T of cyclesbetween successive synchronizing signals; second circuit means,including a gate circuit having its input connected to said firstcircuit means, and storage means connected to the output of said gatecircuit and operable to store the output voltage UR produced during arespective cycle; and third circuit means connected to said first andsecond circuit means and controlling the charging current of saidcondenser, during each cycle Tn, as a function of the amplitude of thestored output voltage UR produced during the immediately preceding cycleTn 1 of said synchronizing signals, n being a whole number designating abase cycle; whereby the sawtooth signal pulse emitted during each cycleis controlled in proportion to the length of the immediately precedingcycle Tn 1 between successive synchronizing signals.
 2. A circuitarrangement, as claimed in claim 1, including fourth circuit meansconnected to said first and second circuit means and deriving, from theoutput voltage UR, corresponding to a cycle Tn between the synchronizingsignals, and the output voltage URn 1, corresponding to the immediatelypreceding cycle Tn l between the synchronizing signals, a differentialvoltage Delta URn and adding said differential voltage Delta URn to saidoutput voltage UR.
 3. A circuit arrangement, as claimed in claim 1 inwhich said first circuit means, providing an output voltage URcorresponding to the cycle T between said synchronizing signals,includes a monostable multivibrator; and a second condenser connected tosaid multivibrator and having its charging controlled by saidmultivibrator to produce a charge voltage uR U1- A/t, in which U1 and Aare circuit constants and t is the instantaneous value of the chargingtime of said second condenser.
 4. A circuit arrangement, as claimed inclaim 3, including fourth circuit means connected to said first andsecond circuit means means connected to said first and second circuitmeans and deriving, from the output voltage UR corresponding to a cycleTn between the synchronizing signals, and the output vOltage URn 1,corresponding to the immediately preceding cycle Tn 1 between thesynchronizing signals, a differential voltage Delta URn and adding saiddifferential voltage Delta URn to said output voltage UR.
 5. A circuitarrangement, as claimed in claim 1, in which said third circuit meanscomprises a solid state current device controlling the charging currentof said first-mentioned condenser, and a transistor conducting thedischarge current of said first-mentioned condenser and connected inparallel with said first-mentioned condenser.
 6. A circuit arrangement,as claimed in claim 5, in which said first circuit means, providing anoutput voltage UR corresponding to the cycle T between saidsynchronizing signals, includes a monostable multivibrator; and a secondcondenser connected to said multivibrator and having its chargingcontrolled by said multivibrator to produce a charge voltage uR U1 -A/t,in which U1 and A are circuit constants and t is the instantaneous valueof the charging time of said second condenser.
 7. A circuit arrangement,as claimed in claim 6, including a transformer having a magnetizablecore and a plurality of windings on said core; said first circuit meansincluding a pulse forming stage having said synchronizing signalsapplied to its input and including a second transistor having anelectrode connected to the input of said pulse forming stage andconnected by a feedback circuit to first and second windings of saidtransformer; said monostable multivibrator comprising a pair of thirdtransistors and being connected to said first transformer winding forcontrol by the latter; a third condenser connected to said multivibratorand periodically charged and discharged by said multivibrator, a fourthcondenser; a first impedance transforming means, consisting of aplurality of transistors, and a first gate circuit, consisting of aplurality of diodes and connected to a third winding of said transformerfor control by said third winding, connecting said fourth condenser tosaid multivibrator; said multivibrator, responsive to a pulsecorresponding to a synchronizing signal, transferring the charge of saidthird condenser to said fourth condenser for storage in said fourthcondenser; a second impedance transforming means consisting of aplurality of transistors connecting said fourth condenser with the baseof a fourth transistor controlling the charging current of saidfirst-mentioned condenser producing the sawtooth voltage; thecollector-emitter circuit of said first transistor being connected inparallel with said first-mentioned condenser, and the base of saidtransistor being connected to said first winding of said transformer;said first transistor being triggered conductive briefly responsive to apulse of said synchronizing signals being applied to its base by saidfirst winding; a sawtooth voltage output terminal included in said thirdcircuit means; and a third impedance transforming means, consisting of aplurality of transistors, connecting said first-mentioned condenser tosaid sawtooth voltage output terminal to provide sawtooth voltage pulsesat said sawtooth voltage output terminal.
 8. A circuit arrangement, asclaimed in claim 7, including fourth circuit means connected to saidfirst and second circuit means and deriving, from the output voltage UR,corresponding to a cycle Tn between the synchronizing signals, and theoutput voltage URn 1, corresponding to the immediately preceeding cycleTn 1, between the synchronizing signals, a differential voltage DeltaURn and adding said differential voltage Delta URn to said outputvoltage UR.
 9. A circuit arrangement, as claimed in claim 8, in whichsaid fourth circuit means includes an input terminal, a second gatecircuit, consistIng of a plurality of diodes, connected to saidlast-named input terminal, a fourth winding of said transformerconnected to and controlling said second gate circuit and a fifthcondenser connected to the output of said second gate circuit; saidfifth condenser storing the voltage applied to said last-named inputwhen said second gate circuit is opened; a fourth impedance transformingmeans, consisting of a plurality of transistors including a fifthtransistor as its input; a sixth condenser connecting the base of saidfifth transistor to said fifth condenser; means connecting the base ofsaid fifth transistor to said last-named input terminal; said sixthcondenser being charged with the voltage difference between the voltagestored in said fifth condenser and the instantaneous voltage at saidlast-name input terminal; an output terminal connected to the lasttransistor of said fourth impedance transforming means, whereby avoltage which is the sum of the voltage difference charged on said sixthcondenser and the voltage stored in said fifth condenser is applied tosaid last-named output terminal during opening of said second gatecircuit and through said fourth impedance transforming means; saidlast-named input terminal being connected with the output of said firstimpedance transforming means and said last-named output terminal beingconnected with the input of said first gate circuit; whereby said fourthcircuit means is interposed between the output of said first impedancetransforming means and the input of said first gate circuit.